Lock



FIG. 1 is a perspective view pf a lock showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a front elevational view thereof, the rear elevational view being a mirror image thereof; and,

FIG. 5 is a left side elevational view thereof, the right side elevational view being a mirror image thereof.

The broken lines adjacent to the shaded area represent the boundaries of the claimed design. Other broken lines represent the portions of the design form no part of the claim. None of the broken lines form part of the claimed design. 

The ornamental design for a lock, as shown and described. 